Severe Persistent Allergic Rhinitis. Inflammation but No Histologic Features of Structural Upper Airway Remodeling

Unraveling the Molecular Threads: A Comprehensive Review of the Pathogenesis and Therapeutic Insights Into Allergic Rhinitis

Allergic rhinitis (AR) is a prevalent inflammatory disorder of the nasal mucosa, triggered by allergen exposure and characterized by symptoms such as sneezing, nasal congestion, itching, and rhinorrhea. This comprehensive review aims to unravel the molecular mechanisms underpinning AR, exploring the pathogenesis from allergen recognition to chronic inflammation and tissue remodelling. Central to the disease are immunoglobulin E (IgE)-mediated hypersensitivity reactions, involving key inflammatory mediators and cellular players such as mast cells, eosinophils, and T cells. Genetic predisposition and environmental factors also play significant roles in susceptibility and disease progression. Therapeutic strategies for AR are varied, ranging from symptomatic relief through antihistamines and nasal corticosteroids to more targeted approaches like allergen-specific immunotherapy. Emerging treatments focus on novel molecular pathways, with a growing emphasis on personalized medicine to optimize patient outcomes. Despite advancements, challenges remain in fully understanding the heterogeneity of AR and developing universally effective treatments. This review synthesizes current knowledge, highlighting critical insights into the molecular basis of AR and their implications for clinical practice. It underscores the need for integrated, multidisciplinary approaches to enhance therapeutic efficacy and calls for ongoing research to address unresolved questions and explore new frontiers in AR management. Through this comprehensive synthesis, the review aims to inform and inspire future research and clinical strategies, ultimately improving the quality of life for individuals affected by AR.

Nasal Lavage Fluid Proteomics Reveals Potential Biomarkers of Asthma Associated with Disease Control

Purpose

Little research has explored the proteomic characteristics of nasal lavage fluid from asthmatic patients. This study aims to investigate whether differentially expressed proteins (DEPs) in nasal lavage fluid can serve as a biomarker to differentiate asthma patients from healthy controls (HCs) and to discern between individuals with well controlled and poorly controlled asthma.

Patients and Methods

We enrolled patients with allergic rhinitis (AR), asthma, or both conditions, and HCs in this study. We recorded patients' demographic and medical history data and administered asthma quality of life questionnaire (AQLQ) and asthma control questionnaire (ACQ). Nasal fluid samples were collected, followed by protein measurements, and proteomic analysis utilizing the data-independent acquisition (DIA) method.

Results

Twenty-four with asthma, 27 with combined asthma+ AR, 25 with AR, and 12 HCs were enrolled. Four proteins, superoxide dismutase 2 (SOD2), serpin B7 (SERPINB7), kallikrein-13 (KLK13), and bleomycin hydrolase (BLMH) were significantly upregulated in nasal lavage fluid samples of asthma without AR, compared to HCs (Fold change ≥2.0, false-discovery rate [FDR] <0.05). Conversely, 56 proteins including secretoglobin family 2A member 1 (SCGB2A1) were significantly downregulated (fold change ≥2.0, FDR <0.05). Furthermore, 96.49% of DEPs including peptidase inhibitor 3 (PI3) and C-X-C motif chemokine 17 (CXCL17) were upregulated in poorly controlled asthma patients without AR relative those with well- or partly controlled asthma (fold change ≥1.5, FDR <0.05). Search tool for the retrieval of interacting genes/proteins (STRING) analysis showed that PI3, with 18 connections, may be pivotal in asthma control.

Conclusion

The study revealed significant alteration in the nasal lavage proteome in asthma without AR patients. Moreover, our results indicated a potential association between the expression of proteome in the upper airway and the level of asthma control. Specifically, PI3 appears to be a key role in the regulation of asthma without AR.

Epithelial SIRT6 governs IL-17A pathogenicity and drives allergic airway inflammation and remodeling

Dysregulation of IL-17A is closely associated with airway inflammation and remodeling in severe asthma. However, the molecular mechanisms by which IL-17A is regulated remain unclear. Here we identify epithelial sirtuin 6 (SIRT6) as an epigenetic regulator that governs IL-17A pathogenicity in severe asthma. Mice with airway epithelial cell-specific deletion of Sirt6 are protected against allergen-induced airway inflammation and remodeling via inhibiting IL-17A-mediated inflammatory chemokines and mesenchymal reprogramming. Mechanistically, SIRT6 directly interacts with RORγt and mediates RORγt deacetylation at lysine 192 via its PPXY motifs. SIRT6 promotes RORγt recruitment to the IL-17A gene promoter and enhances its transcription. In severe asthma patients, high expression of SIRT6 positively correlates with airway remodeling and disease severity. SIRT6 inhibitor (OSS_128167) treatment significantly attenuates airway inflammation and remodeling in mice. Collectively, these results uncover a function for SIRT6 in regulating IL-17A pathogenicity in severe asthma, implicating SIRT6 as a potential therapeutic target for severe asthma.

Semaphorin 7a aggravates TGF-β1-induced airway EMT through the FAK/ERK1/2 signaling pathway in asthma

Background

TGF-β1 can induce epithelial-mesenchymal transition (EMT) in primary airway epithelial cells (AECs). Semaphorin7A (Sema7a) plays a crucial role in regulating immune responses and initiating and maintaining transforming growth factor β1 TGF-β1-induced fibrosis.

Objective

To determine the expression of Sema7a, in serum isolated from asthmatics and non-asthmatics, the role of Sema7a in TGF-β1 induced proliferation, migration and airway EMT in human bronchial epithelial cells (HBECs) in vitro.

Methods

The concentrations of Sema7a in serum of asthmatic patients was detected by enzyme-linked immunosorbent assay (ELISA). The expressions of Sema7a and integrin-β1 were examined using conventional western blotting and real-time quantitative PCR (RT-PCR). Interaction between the Sema7a and Integrin-β1 was detected using the Integrin-β1 blocking antibody (GLPG0187). The changes in EMT indicators were performed by western blotting and immunofluorescence, as well as the expression levels of phosphorylated Focal-adhesion kinase (FAK) and Extracellular-signal-regulated kinase1/2 (ERK1/2) were analyzed by western blot and their mRNA expression was determined by RT-PCR.

Results

We described the first differentially expressed protein of sema7a, in patients with diagnosed bronchial asthma were significantly higher than those of healthy persons (P<0.05). Western blotting and RT-PCR showed that Sema7a and Integrin-β1 expression were significantly increased in lung tissue from the ovalbumin (OVA)-induced asthma model. GLPG0187 inhibited TGF-β1-mediated HBECs EMT, proliferation and migration, which was associated with Focal-adhesion kinase (FAK) and Extracellular-signal-regulated kinase1/2 (ERK1/2) phosphorylation.

Conclusion

Sema7a may play an important role in asthma airway remodeling by inducing EMT. Therefore, new therapeutic approaches for the treatment of chronic asthma, could be aided by the development of agents that target the Sema7a.

Human placental extract regulates polarization of macrophages via IRGM/NLRP3 in allergic rhinitis

Allergic rhinitis (AR) is globally prevalent and its pathogenesis remains unclear. Alternative activation of macrophages is suggested in AR and thought to be involved in natural immunoregulatory processes in AR. Aberrant activation of Nod-like receptor protein 3 (NLRP3) inflammasome is linked with AR. Human placenta extract (HPE) is widely used in clinics due to its multiple therapeutic potential carried by diverse bioactive molecules in it. We aim to investigate the effect of HPE on AR and the possible underlying mechanism. Ovalbumin (OVA)-induced AR rat model was set up and treated by HPE or cetirizine. General manifestation of AR was evaluated along with the histological and biochemical analysis performed on rat nasal mucosa. A proteomic analysis was performed on AR rat mucosa. Mouse alveolar macrophages (MH-S cells) were cultured under OVA stimulation to investigate the regulation of macrophages polarization. The morphological changes and the expression of NLRP3 inflammasome and immunity-related GTPase M (IRGM) in nasal mucosa as well as in MH-S cells were evaluated respectively. The results of our study showed the general manifestation of AR along with the histological changes in nasal mucosa of AR rats were improved by HPE. HPE suppresses NLRP3 inflammasome and the decline of IRGM in AR rats and MH-S cells. HPE regulates macrophage polarization through IRGM/NLRP3. We demonstrated that HPE had protection for AR and the protection is achieved partly through suppressing M1 while promoting M2, the process which is mediated by IRGM via inhibiting NLRP3 inflammasome in AR.

Interleukin‑27 ameliorates allergic asthma by alleviating the lung Th2 inflammatory environment

Interleukin (IL)‑27 can inhibit the differentiation of Th2 cells and plays a role in the development of asthma. However, whether the therapeutic administration of IL‑27 in a mouse model of asthma can inhibit allergic responses remains a matter of debate. Additionally, the mechanisms through which IL‑27 ameliorates inflammatory responses in asthma are not yet fully understood. Thus, the aim of the present study was to examine the effects of IL‑27 on asthma using a mouse model and to elucidate the underlying mechanisms. For this purpose, mice received an intranasal administration of IL‑27 and the total and differential cell counts, levels of cytokines and type 1 regulatory T (Tr1) cells in the lungs were detected. The protein and mRNA levels of signal transducer and activator of transcription (STAT)1 and STAT3 were analyzed and airway remodeling was assessed. The results indicated that IL‑27 did not ameliorate airway inflammation, airway hyperresponsiveness, and airway remolding when administrated therapeutically. Preventatively, the administration of IL‑27 decreased the concentrations of Th2 cytokines and increased the number of Tr1 cells. The protein and mRNA levels of STAT1 and STAT3 were increased. Taken together, these findings demonstrate that the prophylactic administration of IL‑27 ameliorates asthma by alleviating the lung Th2 inflammatory environment through the restoration of both the STAT1 and STAT3 pathways. IL‑27 may thus prove to be useful as a novel agent for the prevention of asthma.

Clinical features and nasal inflammation in asthma and allergic rhinitis

Asthma and allergic rhinitis (AR) are widely considered to be the most common chronic inflammatory disorders. This study was performed to investigate the clinical features, disease severity, and upper airway inflammation among patients with asthma, AR, and asthma comorbid AR. Blood and nasal lavage fluid samples were collected from patients with isolated asthma (n = 23), isolated AR (n = 22), and asthma comorbid AR (n = 22). Demographic data, symptom evaluation, and spirometry were obtained from all subjects. The levels of interleukin (IL)-4, IL-5, IL-13, IL-17, IL-25, IL-33, and S100 proteins were measured in the nasal lavage fluid. Compared with isolated asthma, patients with asthma comorbid AR showed a lower quality of life according to the asthma quality-of-life questionnaire (AQLQ) score (6.11 ± 0.47 vs. 6.45 ± 0.35, P = 0.007). Additionally, no significant difference in the levels of IL-4 (P = 0.116), IL-25 (P = 0.235), and S100A12 (P = 0.392) was observed in nasal lavage fluid among three groups. However, miniscule levels of IL-5, IL-17, IL-13, IL-33, S100A8, and S100A9 were detected in nasal lavage fluid in all three groups. Patients with asthma comorbid AR showed an increased level of systemic cytokine in plasma than that of patients with isolated AR or asthma alone. The finding from our study may help clinicians to better understand the airway inflammation among asthma patients with or without AR.

Identification of gene biomarkers with expression profiles in patients with allergic rhinitis

Background

Allergic rhinitis (AR) is an upper respiratory tract inflammation disease caused by IgE-mediated reactions against inhaled allergens. The incidence of AR is significantly increasing throughout the world. Hence, more specific, and sensitive gene biomarkers and understanding the underlying pathways are necessary to further explore the AR pathogenesis.

Objective

To identify gene biomarkers in nasal mucosa and in blood from AR patients which could be used in AR diagnosis.

Methods

The gene expression profiles of GSE43523 from nasal epithelial cells and GSE75011 from Th2-enriched CD4+ T cells in blood were downloaded from the Gene Expression Omnibus database. Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses and protein–protein interaction (PPI) network analysis were conducted to investigate the functional changes of genes. The receiver operating characteristic (ROC) curves were used to assess the diagnostic values of the hub genes. Real-time quantitative PCR (RT-qPCR) was performed to validate the hub genes.

Results

Significant differentially enriched gene signatures in AR patients were identified in nasal epithelial cells (n-DEGs) and in blood (t-DEGs). Signatures associated with axoneme, extracellular matrix, collagen fibril organization, cell motility, calcium ion binding, and so on were more enriched in n-DEGs, whereas signatures associated with TNF signaling pathway, detoxification of inorganic compound, and cellular response to corticotropin-releasing hormone stimulus were enriched in t-DEGs. In addition, we identified 8 hub genes and 14 hub genes from n-DEGs and t-DEGs, respectively. The combination of POSTN in nasal mucosa and PENK and CDC25A in blood was constructed with a good AR predicting performance. The area under the curve (AUC) of the ROC curve of 3 hub genes’ combination was 0.98 for AR diagnosis.

Conclusion

This study utilized gene expression profiles and RT-qPCR validation on nasal mucosa and blood from AR patients to investigate the potential biomarkers for AR diagnosis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13223-022-00656-4.

Distinct Secretion of MUC5AC and MUC5B in Upper and Lower Chronic Airway Diseases

The human airway is protected by a defensive mucus barrier. The most prominent components of mucus are the mucin glycoproteins MUC5AC and MUC5B. They are produced by goblet cells and submucosal gland cells in the upper and lower airways. Hyperplasia of these cells and hypersecretion of MUC5AC and MUC5B characterize chronic inflammatory diseases of the upper and lower airways. Recent studies have revealed that MUC5AC and MUC5B are expressed at specific sites in the respiratory tract through different molecular mechanisms and have distinct functions. Morphometric and histochemical studies have also examined the roles of goblet cells, submucosal gland cells, MUC5AC, and MUC5B in different chronic airway diseases individually. The individual study of goblet cells, submucosal gland cells, MUC5AC, and MUC5B in airway diseases would be helpful for precisely diagnosing chronic inflammatory diseases of the airway and establishing optimal treatments. This review focuses on the distinct secretion of MUC5AC and MUC5B and their producing cells in chronic inflammatory diseases of the upper and lower airway.

Downregulation of miR‑29b‑3p promotes α‑tubulin deacetylation by targeting the interaction of matrix metalloproteinase‑9 with integrin β1 in nasal polyps

Matrix metalloproteinase (MMP)‑9 is a key enzyme responsible for extracellular matrix degradation and contributes to the progressive histological changes observed in lower respiratory tract infections. Integrin β1 and α‑tubulin are potential MMP‑9‑interacting proteins, and microRNA (miR)‑29b‑3p can regulate MMP‑9 expression. MMP‑9 is highly expressed in chronic rhinosinusitis with nasal polyps (CRSwNPs), regardless of its effects on miR‑29b‑3p, integrin β1 and α‑tubulin expression. In the present study, samples from 100 patients with CRSwNPs were examined via reverse transcription‑quantitative PCR to assess the mRNA expression of miR‑29b‑3p, and western blotting was performed to assess the protein expression of MMP‑2, MMP‑9, acetyl‑α‑tubulin, integrin β1 and tissue inhibitor of metalloproteinase 1 (TIMP‑1). A dual‑luciferase reporter assay was used to verify the direct binding of miR‑29b‑3p and MMP‑2/MMP‑9. Co‑immunoprecipitation (Co‑IP) and GST pull‑down assays showed that integrin β1 and α‑tubulin were MMP‑9‑interacting proteins. Cell viability, apoptosis and inflammatory cytokine levels were determined via a Cell Counting Kit‑8 assay, flow cytometry and ELISA, respectively. miR‑29b‑3p expression was found to be positively correlated with MMP‑2 and MMP‑9 expression. Whereas, TIMP‑1 expression was negatively correlated with MMP‑2 and MMP‑9 expression. The dual‑luciferase assay revealed that miR‑29b‑3p targeted the 3' untranslated region of MMP‑2/MMP‑9. The Co‑IP and GST pull‑down assays showed that MMP‑9 could directly bind to integrin β1 and indirectly bind to α‑tubulin. Finally, the overexpression of miR‑29b‑3p decreased the expression of MMP‑9 and increased the levels of acetyl‑α‑tubulin. By contrast, the knockdown of miR‑29b‑3p increased the expression of MMP‑9 and decreased the levels of acetyl‑α‑tubulin. Additionally, MMP‑9 expression was found to be negatively correlated with acetyl‑α‑tubulin expression. Of note, the expression of integrin β1 did not change following the overexpression and knockdown of MMP‑9. Finally, the overexpression of miR‑29b‑3p not only decreased MMP‑9 expression, but also alleviated lipopolysaccharide‑induced inflammation in NP69 cells. The results showed that the downregulation of miR‑29b‑3p promoted α‑tubulin deacetylation by increasing the number of MMP‑9‑integrin β1 complexes in CRSwNPs, thus targeting miR‑29b‑3p/MMP‑9 may be a potential novel strategy for the clinical treatment of CRSwNPs.

The Role of CD40 in Allergic Rhinitis and Airway Remodelling

Background

Allergic rhinitis (AR) affects millions of people and is lack of effective treatment. CD40 is an important costimulatory molecule in immunity. However, few studies have focused on the role of CD40 in AR.

Methods

In this study, we built mouse model of chronic AR. The mice were divided into the AR, control, intravenous CD40 siRNA, and nasal CD40 siRNA groups (n = 6 each). We detected OVA-sIgE, IL-4, IL-5, IL-13, IL-10, IFN-γ, and TGF-β levels in serum and supernatant by ELISA, CD40⁺ splenic DCs, and Foxp3⁺ Tregs by flow cytometry and CD40 mRNA by RT²-PCR. We also used PAS and MT stains to assess tissue remodelling.

Results

(1) The OVA-sIgE, IL-4, IL-5, and IL-13 levels in the serum or supernatant of nasal septal membrane of AR mice were significantly higher than control. After treated with CD40 siRNA, those indicators were significantly decreased. The IFN-γ, IL-10, and TGF-β levels in AR mice were significantly lower than that in control and were increased by administration of CD40 siRNA. (2) AR mice had significantly fewer Foxp3⁺ Tregs in the spleen than control mice. After treated with CD40 siRNA, AR mice had significantly more Foxp3⁺ Tregs. (3) AR mice exhibited a significantly higher CD40 mRNA levels than control. Administration of CD40 siRNA significantly reduced the CD40 mRNA level. (4) The AR mice showed significantly greater collagen deposition than the control in MT staining. Applications of CD40 siRNA significantly reduced the collagen deposition in AR mice.

Conclusion

CD40 siRNA therapy shows promise for chronic AR as it significantly attenuated allergic symptoms and Th2-related inflammation and upregulated Foxp3⁺ Tregs. CD40 plays a role in tissue remodelling in AR, which can be inhibited by CD40 siRNA application.

Asthma and Chronic Rhinosinusitis: How Similar Are They in Pathogenesis and Treatment Responses?

Severe asthma and rhinosinusitis represent frequent comorbidities, complicating the overall management of the disease. Both asthma and chronic rhinosinusitis (CRS) can be differentiated into endotypes: those with type 2 eosinophilic inflammation and those with a non-type 2 inflammation. A correct definition of phenotype/endotype for these diseases is crucial, taking into account the availability of novel biological therapies. Even though patients suffering from type 2 severe asthma-with or without CRS with nasal polyps-significantly benefit from treatment with biologics, the existence of different levels of patient response has been clearly demonstrated. In fact, in clinical practice, it is a common experience that patients reach a good clinical response for asthma symptoms, but not for CRS. At first glance, a reason for this could be that although asthma and CRS can coexist in the same patient, they can manifest with different degrees of severity; therefore, efficacy may not be equally achieved. Many questions regarding responders and nonresponders, predictors of response, and residual disease after blocking type 2 pathways are still unanswered. In this review, we discuss whether treatment with biological agents is equally effective in controlling both asthma and sinonasal symptoms in patients in which asthma and chronic rhinosinusitis with nasal polyps coexist.

The role of Narrow Band Imaging (NBI) in the diagnosis of sinonasal diseases

BACKGROUND

Narrow band imaging (NBI) endoscopy is an optical method that helps to characterise tissue vasculature. Its appli- cation in sinonasal pathology remains scarce and a systematic study of its application to rhinology is lacking. The aim of this study is to analyse and describe the normal sinonasal mucosa under NBI light and to characterise the microvascular features of various sinonasal pathologies. We also want to suggest a classification of the patterns, peculiar to this district, and to evaluate whether they can be indicative of a specific physiological or pathological condition.

METHODS

Digital videos and images under white light and NBI of 103 patients (82 evaluated) with 29 sinonasal pathologies and 55 controls (33 evaluated). were independently analysed by three otolaryngologists and the final pattern was then arranged for each image, reaching an agreement between the individual evaluations.

RESULTS

Once the appearance of normal sinonasal (SN) mucosa was established (SN1), four patterns for the pathological mucosa were described and a working classification was proposed (SN2, SN3, SN4, SN5). We calculated specificity (80.6% vs 90.6%), sensi- tivity (20% vs 38.5%), PPV (46.1% vs 50%), NPV (54.7% vs 85.7%) and accuracy (53% vs 80.3%) of the ability of SN4 and SN5 pattern to discriminate between benign and malignant nasal neoformations.

CONCLUSIONS

This is the first study to propose a systematic NBI description and a classification of the vasculature of healthy and pathological mucosa in the sinonasal tract. Our preliminary results show that this technique can help in the workup of several rhinologic conditions and especially in distinguishing benign from malignant tumors.

Allergic rhinitis

Allergic rhinitis (AR) is caused by immunoglobulin E (IgE)-mediated reactions to inhaled allergens and is one of the most common chronic conditions globally. AR often co-occurs with asthma and conjunctivitis and is a global health problem causing major burden and disability worldwide. Risk factors include inhalant and occupational allergens, as well as genetic factors. AR impairs quality of life, affects social life, school and work, and is associated with substantial economic costs. The Allergic Rhinitis and its Impact on Asthma (ARIA) initiative classified AR into intermittent or persistent and mild or moderate/severe. The diagnosis is based on the clinical history and, if needed in patients with uncontrolled rhinitis despite medications or with long-lasting symptoms, on skin tests or the presence of serum-specific IgE antibodies to allergens. The most frequently used pharmacological treatments include oral, intranasal or ocular H₁-antihistamines, intranasal corticosteroids or a fixed combination of intranasal H₁-antihistamines and corticosteroids. Allergen immunotherapy prescribed by a specialist using high-quality extracts in stratified patients is effective in patients with persistent symptoms. Real-world data obtained by mobile technology offer new insights into AR phenotypes and management. The outlook for AR includes a better understanding of novel multimorbid phenotypes, health technology assessment and patient-centred shared decision-making.

Repetitive nasal allergen challenge in allergic rhinitis: Priming and Th2-type inflammation but no evidence of remodelling

BACKGROUND

Local tissue eosinophilia and Th2 cytokines are characteristic features of seasonal allergic rhinitis. Airway remodelling is a feature of asthma whereas evidence for remodelling in allergic rhinitis (AR) is conflicting.

OBJECTIVE

By use of a novel human repetitive nasal allergen challenge (RAC) model, we evaluated the relationship between allergic inflammation and features of remodelling in AR.

METHODS

Twelve patients with moderate-severe AR underwent 5 alternate day challenges with diluent which after 4 weeks were followed by 5 alternate day challenges with grass pollen extract. Nasal symptoms, Th1/Th2 cytokines in nasal secretion and serum were evaluated. Nasal biopsies were taken 24 hours after the 1st and 5th challenges with diluent and with allergen. Sixteen healthy controls underwent a single challenge with diluent and with allergen. Using immunohistochemistry, epithelial and submucosal inflammatory cells and remodelling markers were evaluated by computed image analysis.

RESULTS

There was an increase in early and late-phase symptoms after every allergen challenge compared to diluent (both P < .05) with evidence of both clinical and immunological priming. Nasal tissue eosinophils and IL-5 in nasal secretion increased significantly after RAC compared to corresponding diluent challenges (P < .01, P = .01, respectively). There was a correlation between submucosal mast cells and the early-phase clinical response (r = 0.79, P = .007) and an association between epithelial eosinophils and IL-5 concentrations in nasal secretion (r = 0.69, P = .06) in allergic rhinitis. No differences were observed after RAC with regard to epithelial integrity, reticular basement membrane thickness, glandular area, expression of markers of activation of airway remodelling including α-SMA, HSP-47, extracellular matrix (MMP7, 9 and TIMP-1), angiogenesis and lymphangiogenesis for AR compared with healthy controls.

CONCLUSION

Novel repetitive nasal allergen challenge in participants with severe persistent seasonal allergic rhinitis resulted in tissue eosinophilia and increases in IL-5 but no structural changes. Our data support no link between robust Th2-inflammation and development of airway remodelling in AR.

Intermittent hypoxia induces turbinate mucosal hypertrophy via upregulating the gene expression related to inflammation and EMT in rats

PURPOSE

Chronic intermittent hypoxia (IH) plays a pivotal role in the consequences of obstructive sleep apnea (OSA). It has been demonstrated that IH impairs nasomaxillary complex growth to reduce nasal airway cavity size in rodent models. Although turbinate dysfunction with inflammatory mucosal hypertrophy is related to OSA, the role of IH in turbinate hypertrophy with inflammation-driven fibrosis is unknown. Here, we aimed to clarify the pathogenesis of inflammatory mucosal hypertrophy and epithelial-mesenchymal transition (EMT) in the nasal turbinate under IH.

METHODS

Seven-week-old male Sprague-Dawley rats were exposed to IH (4% O₂ to 21% O₂ with 0% CO₂) at a rate of 20 cycles/h.

RESULTS

Hypertrophy of the turbinate mucosa occurred after 3 weeks, with the turbinate mucosa of the experimental group becoming significantly thicker than in the control group. Immunostaining showed that IH increased the expression of TGFβ and N-cadherin and decreased E-cadherin expression in the turbinate mucosa. Quantitative PCR analysis demonstrated that IH enhanced the expression of not only the inflammatory markers Tnf-a, Il-1b, and Nos2 but also the EMT markers Tgf-b1, Col1a1, and Postn.

CONCLUSIONS

Collectively, these results suggest that IH induced turbinate hypertrophy via upregulation of gene expression related to inflammation and EMT in the nasal mucosa.

Nasal lavage cytology and mucosal histopathological alterations in patients with rhinitis

Introduction

The extent of epithelial lesion in allergic and non-allergic rhinitis and its association with inflammatory changes in nasal lavage has not been clarified.

Objective

To verify the association between the inflammatory cells in the nasal lavage, epithelial lesion extent and basement membrane thickness, in the nasal mucosa of patients with rhinitis; to determine the cutoff point of the percentage of eosinophils in the nasal lavage associated with the atopic patients.

Methods

Patients with rhinitis and indication for septoplasty and (or) turbinectomy for turbinate hypertrophy were selected, and were submitted to allergy skin tests, nasal lavage with measurement of albumin and interleukin-8 levels, total and differential counting of cells, and mucosal histopathological analysis to determine the extent of epithelial lesion, and degree of basement membrane thickening.

Results

Fifty-six patients with a median age of 24.5 years and a diagnosis of allergic rhinitis (n = 36) and non-allergic rhinitis (n = 20) were studied. In atopic subjects, allergy skin tests were positive for Dermatophagoides pteronyssinus in 35 (97.0%) and Lolium perenne in 18 (50.0%). Atopic subjects showed a higher clinical score index of rhinitis compared to non-atopic ones. The total count of cells, neutrophils, and levels of albumin and IL-8 were not different in the nasal lavage of atopic and non-atopic subjects. The cutoff point for eosinophil count in nasal fluid for the distinction between allergic rhinitis and non-allergic rhinitis was 4%. Some degree of epithelial lesion was more frequent in allergic rhinitis (94%) than in non-allergic rhinitis (65%) patients. In the presence of basement membrane thickness, as a marker of remodeling, there was no difference in the nasal lavage of patients with allergic rhinitis and non-allergic rhinitis.

Conclusion

In this series, 4% was the cutoff point for the number of eosinophils in the nasal lavage, for atopy differentiation. Upper airway remodeling accessed by basement membrane thickness showed similar inflammatory cell infiltrate in the nasal lavage, regardless of the presence of atopy.

IL‑27 suppresses airway inflammation, hyperresponsiveness and remodeling via the STAT1 and STAT3 pathways in mice with allergic asthma

Type 2 cytokine-associated immunity may be involved in the pathogenesis of allergic asthma. Although interleukin 27 (IL-27) has been reported as an initiator and suppressor of T-helper 1 (Th1) and T-helper 2 (Th2) responses, respectively, its effects on the development of asthma remain unclear. In the present study, mice were induced and challenged with ovalbumin and received subsequent intranasal administration of IL-27. Total and differential cell counts were determined from Wright-Giemsa-stained cytospins, whereas the cytokine levels were detected using ELISA. In addition, the expression levels of signal transducer and activator of transcription (STAT) 1, STAT3, GATA-binding protein-3 (GATA3) and T-bet (T-box transcription factor) were analyzed in T cells by western blot analysis. Their corresponding mRNA expression levels were determined by quantitative PCR. Airway remodeling was assessed by conventional pathological techniques. The results indicated that intranasal administration of IL-27 ameliorated airway inflammation and hyperresponsiveness in an acute model of asthma. Furthermore, IL-27 prevented airway remodeling in a chronic model of asthma. Following administration of IL-27, the mRNA expression levels of STAT1 and T-bet were upregulated, while those of GATA3 were downregulated. Moreover, the phosphorylation levels of STAT1 and STAT3 were increased. Taken together, these findings demonstrated that intranasal administration of IL-27 ameliorated Th2-related allergic lung inflammation and remodeling in mouse models of asthma by repairing both the STAT1 and STAT3 pathways.

Recent developments and highlights in allergic rhinitis

Allergic rhinitis (AR) is a disease with high prevalence all over the world and therefore needs to be thoroughly investigated and treated accordingly. The mechanisms underlying the pathology and treatment of AR have been widely studied, but many aspects remain unclear and warrant further investigations. This review presents an overview of recently published papers highlighting the risk factors, mechanisms, and treatment of AR. Additionally, recent studies discussing the role of single nucleotide polymorphism, DNA methylation, regulatory B cells, group 2 innate lymphoid cells, immunotherapy, and biologics in AR are also covered.

Insight into interleukin-37: The potential therapeutic target in allergic diseases

Allergic diseases are ubiquitous diseases with detrimental effects on the quality of life of people worldwide. Common allergic diseases include asthma, allergic rhinitis (AR) and allergic dermatitis (AD). Recently, studies have shown that interleukin (IL)-37, a novel cytokine in the IL-1 family, exhibits broad protective properties in various diseases, such as autoimmune diseases and cancer. IL-37 displays its anti-inflammatory effect on diseases by curbing innate and acquired immunity as well as inflammatory reactions. IL-37 functions by forming a complex with IL-18Rα and IL-1R8 extracellularly and can be translocated to the nucleus upon forming a complex with mothers against decapentaplegic homolog 3 (Smad3) intracellularly, thereby affecting gene transcription and signaling pathway activation. In addition, increasing evidence confirms that IL-37 expression is aberrant in asthma, AR and AD, which indicates that IL-37 may also play essential roles in allergic diseases. Furthermore, accumulating data obtained from recombinant IL-37 (rIL-37)-treated mice and from IL-37 transgenic (IL-37tg) mice suggest a protective role for IL-37. This review will detail the role of IL-37 in the occurrence and development of allergic diseases and discuss the potential of IL-37 as a therapeutic target in allergic diseases.

Serum IL-1β can be a biomarker in children with severe persistent allergic rhinitis

Background

Allergic rhinitis (AR) is one of the most common diseases globally and usually persists throughout life. In the present study, we aimed to determine whether the expression of inflammatory biomarkers has a relationship with the severity of allergic rhinitis and with comorbid asthma or other allergic diseases in children.

Methods

For diagnosis of AR, the skin prick test was performed to measure the responses to 18 allergens. Blood levels of eosinophils and immunoglobulin E (IgE) were examined. We classified the patients into 2 groups based on the severity of the condition as Group 1 [intermittent AR (IAR) or mild persistent AR (PAR)] and Group 2 (moderate to severe PAR). To determine the expression of inflammatory biomarkers, in serum and several biomarkers (caspase-1, IL-1β, CCL-11, CCL-24 and IL-33) were measured in the serum using enzyme-linked immunosorbent assay (ELISA). Additionally, we analyzed the correlation between clinical variables and the expression of biomarkers (eosinophils count, IL-1β and CCL-24) and the severity of AR.

Results

We found that eosinophils count, IL-1β, a marker of activation of inflammasomes, and CCL-24 were significantly increased in the moderate to severe PAR group (p = 0.008, p = 0.003, p = 0.039). Additionally, the expressions of eosinophil count, IL-1β and CCL-24 were significantly higher in patients with active asthmatic symptoms than in those without these conditions. On univariate analysis, allergic rhinitis in sibling, paternal allergic rhinitis, high expression of eosinophils count, IL-1β and CCL-24, history of active asthma and atopy correlated with severity of AR. Multivariate analysis showed only paternal allergic rhinitis and high expression of IL-1β as significant risk factors of moderate to severe PAR with 6.4 fold and 4.7 fold-increase in risk, respectively (p = 0.011 and p = 0.030).

Conclusion

In conclusion, this study provides the first evidence that an excessive release of biologically active IL-1β may promote inflammation in severe PAR. It demonstrates that IL-1β can be a biomarker for active allergic diseases such as AR, asthma, and atopy. Moreover, this finding suggests that IL-1B should be investigated as a therapeutic target in severe PAR and other allergic diseases.

Biological Effects of Thermal Water-Associated Hydrogen Sulfide on Human Airways and Associated Immune Cells: Implications for Respiratory Diseases

Natural mineral (thermal) waters have been used for centuries as treatment for various diseases. However, the scientific background of such therapeutic action is mostly empiric and based on knowledge acquired over time. Among the various types of natural mineral waters, sulfurous thermal waters (STWs) are the most common type in the center of Portugal. STWs are characterized by high pH, poor mineralization, and the presence of several ions and salts, such as bicarbonate, sodium, fluoride, silica, and carbonate. Furthermore, these waters are indicated as a good option for the treatment of various illnesses, namely respiratory diseases (e.g., allergic rhinitis, asthma, and chronic obstructive pulmonary disease). From the sulfide species present in these waters, hydrogen sulfide (H₂S) stands out due to its abundance. In healthy conditions, H₂S-related enzymes (e.g., cystathionine β-synthase and cystathionine γ-lyase) are expressed in human lungs, where they have mucolytic, antioxidant, anti-inflammatory, and antibacterial roles, thus contributing to airway epithelium homeostasis. These roles occur mainly through S-sulfhydration, a post-translational modification through which H₂S is able to change the activity of several targets, such as ion channels, second messengers, proteins, among others. However, in respiratory diseases the metabolism of H₂S is altered, which seems to contribute somehow to the respiratory deterioration. Moreover, H₂S has been regarded as a good biomarker of airway dysfunction and severity, and can be measured in serum, sputum, and exhaled air. Hence, in this review we will recapitulate the effects of STWs on lung epithelial-immune crosstalk through the action of its main component, H₂S.

Serum leptin levels correlate negatively with the capacity of vitamin D to modulate the in vitro cytokines production by CD4+ T cells in asthmatic patients

Both obesity and low vitamin D levels have been associated with allergic asthma (AA) severity. In the present study, severity of AA was associated with obesity but to the in vitro IgE production. In those patients, higher levels of IL-5, IL-6 and IL-17 were quantified in CD4⁺ T-cell cultures as compared with patients with mild and moderate AA. In addition, the lowest IL-10 levels were detected in the cell cultures from patients with a worse prognosis. Interestingly, the occurrence of AA elevates the plasma levels of leptin, and this adipokine was positively correlated with the release of IL-5, IL-6 and IL-17, but inversely correlated with IL-10 production, by CD4⁺ T-cells from patients. In AA-derived CD4⁺ T-cell cultures, 1,25(OH)2D3 was less efficient at inhibiting IL-5, IL-6 and IL-17 production, and up regulating IL-10 release, as those from healthy subjects. Interestingly, the in vitro immunomodulatory effects of vitamin D were inversely correlated with serum leptin levels. In summary, our findings suggested that obesity, probably due to the overproduction of leptin, negatively impacts AA as it favors imbalance between Th2/Th17 and regulatory phenotypes. The deleterious effects of leptin may also be due to its ability to counter-regulate the immunosuppressive effects of vitamin D.

Effect of Astragalus membranaceus in Ovalbumin-Induced Allergic Rhinitis Mouse Model

Background

Astragalus membranaceus (AM), a traditional Chinese medicine, has been used to treat allergic diseases, but the mechanism for treating allergic rhinitis (AR) remains unclear.

Objective

The purpose of this study was to look at the anti-inflammatory effect of AM on AR and the mechanism of anti-allergy.

Methods

The mouse model of AR was induced by ovalbumin. Allergic symptoms, number of eosinophils in nasal mucosa, and levels of inflammatory cells in nasal lavage fluid were analyzed. We explored the serum immunoglobulin E (IgE), interleukin-4 (IL-4), IL-5, IL-13, interferon-γ (IFN-γ), and IL-10. Besides, the relative mRNA of IL-4, IL-5, and IL-13 was also detected in nasal mucosa tissue. The proportion of CD4+ CD25+ Foxp3+ T cells in the spleen and nasal lymphoid tissue were analyzed. The mRNA levels of nuclear factor-kappa B p65 (NF-κB p65) and inhibitory kappa B alpha (IκBα), as well as NF-κB p65 DNA binding activity, were tested. We also measured the protein levels of NF-κB p65 and p-NF-κB p65 in nasal mucosa.

Results

AM could reduce the number of eosinophils in the nasal mucosa and decrease the levels of inflammatory cells in nasal lavage fluid. The serum IgE, IL-4, IL-5, and IL-13 were also decreased, while levels of IFN-γ and IL-10 were increased. The relative mRNA of IL-4, IL-5, and IL-13 was decreased by AM. AM increased the proportion of CD4+ CD25+ Foxp3+ T cells in the spleen and nasal lymphoid tissue. In addition, AM could reduce the activity of NF-kB by inhibiting the mRNA expression and DNA binding activity of NF-κB p65. However, AM had no significant effect on mRNA of IκBα. Above all, AM could reduce the p-NF-κB p65 protein expression of nasal mucosa.

Conclusions

AM could reduce the secretion of inflammatory cytokines by increasing the level of CD4+ CD25+ Foxp3+ T cells and inhibiting the activation of the NF-κB.

Upper and lower airway remodelling mechanisms in asthma, allergic rhinitis and chronic rhinosinusitis: The one airway concept revisited

Allergic rhinitis (AR), chronic rhinosinusitis (CRS) and asthma often co-exist. The one airway model proposes that disease mechanisms occurring in the upper airway may mirror lower airway events. Airway remodelling is the term used to describe tissue structural changes that occur in a disease setting and reflect the dynamic process of tissue restructuring during wound repair. Remodelling has been long identified in the lower airways in asthma and is characterized by epithelial shedding, goblet cell hyperplasia, basement membrane thickening, subepithelial fibrosis, airway smooth muscle hyperplasia and increased angiogenesis. The concept of upper airway remodelling has only recently been introduced, and data so far are limited and often conflicting, an indication that more detailed studies are needed. Whilst remodelling changes in AR are limited, CRS phenotypes demonstrate epithelial hyperplasia, increased matrix deposition and degradation along with accumulation of plasma proteins. Despite extensive research over the past years, the precise cellular and molecular mechanisms involved in airway remodelling remain incompletely defined. This review describes our current rather limited understanding of airway remodelling processes in AR, CRS and asthma and presents mechanisms both shared and distinct between the upper and lower airways. Delineation of shared and disease-specific pathogenic mechanisms of remodelling between the sinonasal system and the lung may guide the rational design of more effective therapeutic strategies targeting upper and lower airways concomitantly and improving the health of individuals with inflammatory airway diseases.

International Consensus Statement on Allergy and Rhinology: Allergic Rhinitis

BACKGROUND

Critical examination of the quality and validity of available allergic rhinitis (AR) literature is necessary to improve understanding and to appropriately translate this knowledge to clinical care of the AR patient. To evaluate the existing AR literature, international multidisciplinary experts with an interest in AR have produced the International Consensus statement on Allergy and Rhinology: Allergic Rhinitis (ICAR:AR).

METHODS

Using previously described methodology, specific topics were developed relating to AR. Each topic was assigned a literature review, evidence-based review (EBR), or evidence-based review with recommendations (EBRR) format as dictated by available evidence and purpose within the ICAR:AR document. Following iterative reviews of each topic, the ICAR:AR document was synthesized and reviewed by all authors for consensus.

RESULTS

The ICAR:AR document addresses over 100 individual topics related to AR, including diagnosis, pathophysiology, epidemiology, disease burden, risk factors for the development of AR, allergy testing modalities, treatment, and other conditions/comorbidities associated with AR.

CONCLUSION

This critical review of the AR literature has identified several strengths; providers can be confident that treatment decisions are supported by rigorous studies. However, there are also substantial gaps in the AR literature. These knowledge gaps should be viewed as opportunities for improvement, as often the things that we teach and the medicine that we practice are not based on the best quality evidence. This document aims to highlight the strengths and weaknesses of the AR literature to identify areas for future AR research and improved understanding.

Mechanisms of allergen immunotherapy for inhaled allergens and predictive biomarkers

Allergen immunotherapy is effective in patients with IgE-dependent allergic rhinitis and asthma. When immunotherapy is given continuously for 3 years, there is persistent clinical benefit for several years after its discontinuation. This disease-modifying effect is both antigen-specific and antigen-driven. Clinical improvement is accompanied by decreases in numbers of effector cells in target organs, including mast cells, basophils, eosinophils, and type 2 innate lymphoid cells. Immunotherapy results in the production of blocking IgG/IgG₄ antibodies that can inhibit IgE-dependent activation mediated through both high-affinity IgE receptors (FcεRI) on mast cells and basophils and low-affinity IgE receptors (FcεRII) on B cells. Suppression of T_H2 immunity can occur as a consequence of either deletion or anergy of antigen-specific T cells; induction of antigen-specific regulatory T cells; or immune deviation in favor of T_H1 responses. It is not clear whether the altered long-term memory resides within the T-cell or the B-cell compartment. Recent data highlight the role of IL-10-producing regulatory B cells and "protective" antibodies that likely contribute to long-term tolerance. Understanding mechanisms underlying induction and persistence of tolerance should identify predictive biomarkers of clinical response and discover novel and more effective strategies for immunotherapy.

Inflammation and airway remodeling of the lung in guinea pigs with allergic rhinitis

Allergic rhinitis (AR) and asthma belong to the category of type I allergic diseases, whose pathological features are airway remodeling of the lung and allergic inflammation. The aim of the present study was to evaluate inflammation and remodeling of lung tissue in a guinea pig model of AR in order to confirm consistent pathological changes of upper and lower airways in AR. Male guinea pigs were randomly divided into an experimental and a control group (n=10 in each). The AR model was established by sensitization through intraperitoneal injection of ovalbumin for three weeks and bilateral nasal local excitation for twelve weeks. All tissues of nasal mucosa and lung were subjected to hematoxylin and eosin as well as toluidine blue staining, and characteristics of remodeling of lung tissue, including thickness of bronchial wall, epithelial mucosa and smooth muscle were histologically determined. Collagen deposition in lung tissue was observed by Masson's trichrome stain. Severe paroxysmal nose scratching action, frequent sneezing, visible outflow of secretion from the anterior naris and frequent nose friction were observed in the AR model group within 30 min after local excitation. The total symptom scores were significantly increased in the AR model group compared with those in the control group. Obvious inflammatory cell infiltration was observed in the AR model group. Compared with those in the control group, the numbers of eosinophils and mast cells in nasal mucosa and lung tissue were significantly increased. Obvious airway remodeling of the lung was observed in the AR model group. Compared with those in the control group, bronchial wall thickness, epithelial layer thickness and smooth muscle thickness in the airways were significantly increased in the AR model group. Increased collagen deposition was found in the AR model group compared with that in the control group. The results of the present study revealed that inflammation and airway remodeling of lungs arose in guinea pigs with AR, suggesting that pathological changes of upper and lower airways are consistent in this AR model.

Lymphangiogenesis: fuel, smoke, or extinguisher of inflammation's fire?

Lymphangiogenesis is a recognized hallmark of inflammatory processes in tissues and organs as diverse as the skin, heart, bowel, and airways. In clinical and animal models wherein the signaling processes of lymphangiogenesis are manipulated, most studies demonstrate that an expanded lymphatic vasculature is necessary for the resolution of inflammation. The fundamental roles that lymphatics play in fluid clearance and immune cell trafficking from the periphery make these results seemingly obvious as a mechanism of alleviating locally inflamed environments: the lymphatics are simply providing a drain. Depending on the tissue site, lymphangiogenic mechanism, or induction timeframe, however, evidence shows that inflammation-associated lymphangiogenesis (IAL) may worsen the pathology. Recent studies have identified lymphatic endothelial cells themselves to be local regulators of immune cell activity and its consequential phenotypes - a more active role in inflammation regulation than previously thought. Indeed, results focusing on the immunocentric roles of peripheral lymphatic function have revealed that the basic drainage task of lymphatic vessels is a complex balance of locally processed and transported antigens as well as interstitial cytokine and immune cell signaling: an interplay that likely defines the function of IAL. This review will summarize the latest findings on how IAL impacts a series of disease states in various tissues in both preclinical models and clinical studies. This discussion will serve to highlight some emerging areas of lymphatic research in an attempt to answer the question relevant to an array of scientists and clinicians of whether IAL helps to fuel or extinguish inflammation. Impact statement Inflammatory progression is present in acute and chronic tissue pathologies throughout the body. Lymphatic vessels play physiological roles relevant to all medical fields as important regulators of fluid balance, immune cell trafficking, and immune identity. Lymphangiogenesis is often concurrent with inflammation and can potentially aide or worsen disease progression. How new lymphatic vessels impact inflammation and by which mechanism is an important consideration in current and future clinical therapies targeting inflammation and/or vasculogenesis. This review identifies, across a range of tissue-specific pathologies, the current understanding of inflammation-associated lymphangiogenesis in the progression or resolution of inflammation.

Early Intervention Improves Clinical Responses to House Dust Mite Immunotherapy in Allergic Rhinitis Patients

BACKGROUND

Allergen immunotherapy (AIT) is the unique causal treatment for respiratory allergy. As AIT is expensive and of long duration, the availability of a marker predicting AIT responders is of crucial relevance.

OBJECTIVE

To investigate clinical parameters correlated with effective AIT in allergic rhinitis (AR) patients.

METHODS

This is a prospective, nonrandomized open study in which a total of 284 AR patients who had received house dust mite (HDM) subcutaneous AIT were enrolled from January 2011 to December 2015, and then followed up for 3 consecutive years. Demographic data, clinical history, laboratory tests (specific and total IgE levels), symptoms score, concomitant medication, and adverse reactions during AIT were collected. An AIT responder patient was defined when a visual analog score (assessing global symptoms) had decreased by >30% compared to baseline and concomitant medication was equal to or less than before AIT.

RESULTS

Thirty-three patients dropped out, so 251 patients were analyzed; 175 (69.7%) patients were responders. This group had a higher baseline symptom score than the AIT nonresponder group (7.5 vs. 6.9). A significant negative correlation was found between AR symptom duration and the clinical response to AIT. Local reactions (LRs) during AIT had a positive correlation. Other variables such as a family history of atopy, combined asthma history, and the levels of specific and total IgE had no correlations with effective AIT.

CONCLUSION

Early intervention with AIT helps to improve the efficacy of AR treatment. LRs might predict successful AIT. Highly symptomatic AR patients may develop increased clinical responses to AIT.

Lymphangiogenesis in rat asthma model

Although bronchial angiogenesis has been well documented in allergic asthma, lymphangiogenesis has not been widely studied. Therefore, we evaluated changes in lung lymphatics in a rat model of allergen-induced asthma using house dust mite (Der p 1; 100 μg/challenge). Additionally, properties of isolated lung lymphatic endothelial cells (CD45^-, CD141⁺, LYVE-1⁺, Prox-1⁺) were studied in vitro. Three weeks after the onset of intranasal allergen exposure (twice-weekly), an increase in the number of lung lymphatic vessels was measured (34% increase) by lung morphometry. New lymphatic structures were seen predominantly in the peribronchial and periarterial interstitial space but also surrounding large airways. Isolated lymphatic endothelial cells from sensitized lungs showed enhanced proliferation (% Ki67⁺), chemotaxis, and tube formation (number and length) compared to lymphatic endothelial cells isolated from naive rat lungs. This hyper-proliferative lymphangiogenic phenotype was preserved through multiple cell passages (2-8). Lymphatic endothelial cells isolated from naive and HDM-sensitized rats produced similar in vitro levels of VEGF-C, VEGF-D, and VEGFR3 protein, each recognized as critical lymphangiogenic factors. Inhibition with anti-VEGFR (axitinib, 0.1 μM) blocked proliferation and chemotaxis. Results suggest that in vivo sensitization causes fundamental changes to lymphatic endothelium, which are retained in vitro, and may relate to VEGFR downstream signaling.